Interaction Of Hyperbranched Poly(Amine) Ester Ferrocene With Protein And Its Anion Recognition

Hyperbranched ferrocene combines the three-dimensional structure of hyperbranched polymer with the functionality of ferrocene and units both of special structure of hyperbranched polymer and functionality of ferrocene. The interaction between hyperbranched ferrocene and protein can simulate the interaction form of pathogens with protein since the size and the structure of hyperbranched ferrocene are similar to bacterium, virus and cancer cells. Serum albumin is one of the most important biological molecule in organism and can combine with many molecules. It is significant to the regular live because small molecules, drug molecules and metabolin is transported by serum albumin. The electrochemical properties of ferrocene polymers are the basis for their application and hyperbranched ferrocene possesses particular redox. So study on the interaction between hyperbranched ferrocene and protein can provide theoretical reference for its application in drug carrier, antiviral medicine and biosensor.The interactional mechanism of HPAE-Fc and BSA was researched by fluorescence emission spectrophotometry, ultraviolet spectroscopy, synchronous fluorescence spectrometry and three-dimensional fluorescence spectrometry. The quenching mechanism of BSA was analyzed; binding constant, binding sites and corresponding thermodynamic parameters (ΔG, ΔH and ΔS) was calculated; types of interaction force was indicated; energy transfer mode was analyzed by calculating overlap integral; the interactional mechanism of HPAE-Fc and BSA was explored. The interaction of HPAE-Fc and BSA was compared with HPAE, Fc-COOH. The differences of interactional mechanism was studied. So the particularity of the interaction between HPAE-Fc and BSA was obtained. The complex of HPAE-Fc/BSA was obtained by the chemical reaction and structures of the complexes was characterized by FT-IR. Films of HPAE-Fc and HPAE-Fc/BSA were deposited on the surface of platinum electrode by self-assembly(SA). The electrochemical behaviors of the films and solutions were investigated via cyclic voltammetry(CV) and differential pulse voltammetry(DPV). Because of the electrochemical properties, the anion recognition of HPAE-Fc was researched. HPAE-Fc could recognize Br", HSO4-and ATP2" and the recognition of HPAE-Fc and Fc-COOH was compared. The linear relations of Epu, ΔEP with anion concentration were obtained by fitting a straight line, so the different responsiveness of HPAE-Fc and Fc-COOH was studied.Fluorescent spectrometry investigations show that the reaction between HPAE-Fc and BSA is spontaneous and the fluorescence quenching mechanism of BSA is static quenching process. There is one independent binding site between HPAE-Fc and BSA. The interaction force between HPAE-Fc and BSA is hydrogen bond and Van der Waals force and the energy transport mode is non-radiation energy transfer. The conformation of BSA and hydrophobicity of the environment arounding tryptophan and tyrosine are changed due to the influence of HPAE-Fc. By comparison, the interaction of HPAE, Fc-COOH with BSA is weaker than that of HPAE-Fc. The quenching level of BSA is small and interaction force is major hydrophobic interaction and electrostatic attraction. Moreover the conformation of BSA and hydrophobicity of the environment arounding amino acid are changed smaller.The investigations of different electrochemical solutions show that HPAE-Fc has good electrochemical responsiveness and single redox peak. HPAE-Fc/BSA solution show weaker redox peak than that of HPAE-Fc. However, the redox spike potentials (Epa and Epc) of HPAE-Fc/BSA solution are larger than that of HPAE-Fc solution with AEP increases and peak current reduces. The results indicats that there are significant interactions between HPAE-Fc and BSA. There only reduction peak in HPAE-Fc film electrode can be found and no anodic peak can be seen, also, HPAE-Fc/BSA modified electrodes show double and tailing peaks. The complicated redox properties are probably caused by electrostatic adsorption and hydrogen bond between HPAE-Fc and large biological molecule.The responsiveness of HPAE-Fc was studied by cyclic voltammetry(CV). The receptor of HPAE-Fc exhibits selectivity to Br-, HSO4-and ATP2-. Along with the increasing of anion concentration, Ep1/2of HPAE-Fc increases and ΔEp Ep reduces continuously. The linear relation among Ep1/2, Δ Ep and anion concentration are obtained, so anion recognition and concentration detection are achieved by this liner relation. The results have revealed the interaction mechanism between BSA and other exogenous molecules which could provide theoretical guidance for explaining the versatility of the interaction between BSA and exogenous molecular and extending the application of HPAE-Fc.